Going to install the Windows Vista soon, have 2GB now, do I need 4GB?

How will it run?

2 GiB is a good base amount for Vista. Needing more than 2 GiB is determined by what you intend to use on it.

Vista 32 bit can handle up to 4gb. Vista 64 can handle 8gb up to 128gb depending on which version you are running. Vista 32 bit runs OK with 2gb but you will get better performance and a better Vista rate number with 4gb.

32-bit Vista can "handle" 4GB, in that it won't crash with it. But you won't be able to utilize all of it.

I use vista 64-bit fine with 1GB

the memory Gb is ok for Vista so adding add 2Gb would boost the performance even more

Low end vista 2 GB is fine. higher end and apps, you are going to need 4Gb.
I have ultimate, and run photo editing software and Im up at 75% a lot of the time with 4GB.

With Vista, the more memory you have, the more it will use (like most OS's to keep swapping to a minimum).

I ran Vista 32bit with 2GiB for quite some time, running all latest games (Crysis et al), Photoshop, InDesign etc and it was perfectly quick.

So really, unless your application really needs more than 2GiB, 2 is perfectly fine for Vista.

Vista will run "okay" on 2 gigs but you will get significant performance decrease over XP. If you use 4 gigs for Vista, unless it's 64-bit, it will speed up some (depending on your videocard) but I doubt you will see a dramatic change. I'd still get 4 gigs specially seeing how cheap ram is nowadays.

actually, 256MBs is usually enough to run vista and at least 512MBs if you plan on playing some demanding games like crysis or something